The present invention relates to double cylinder knitting machines and their operation, and more particularly to method and means for transferring knitting from needles of one cylinder to needles of the other cylinder of a double cylinder knitting machine.
As is well known, the plain, regular or knit stitches are formed in double cylinder knitting machines on the needles of the lower cylinder, whereas purl stitches are formed on the needles of the upper cylinder. It is also known that in the construction of rib knitting and in any cases where plain and purl stitches are combined in knitting, the knitting is done on the upper and lower cylinders selectively and alternatively; therefore, in order to change from plain stitches to purl stitches and vice versa, it is necessary to transfer the stitches held by the needles from one cylinder to the other cylinder.
Heretofore, transferring of stitches on a double cylinder knitting machine has conventionally been accomplished with double-hook needles that are themselves transferred from one cylinder to the other while retaining a stitch or knit loop thereon. The advantage of this prior transferring is that it causes little problem in the actual transfer of the stitches themselves from one hook to the other, as both hooks are on the same needle. However, because the needles must be transferred from one cylinder to the other, complicated mechanical systems are necessary with attendant breaking and bending problems, and due to the amplitude of the required axial motions of the double-hook needles, the speed of operation must be significantly limited.
Another prior art arrangement effects transfer using specially formed single-hook needles so that opposing needles can be slid side-by-side with hooks overlapping to transfer stitches from the needle of one cylinder into the hook of the adjacent needle of the other cylinder. This arrangement, however, requires special needles with heads, or hooks, slightly offset from the shank, or thinned to half the thickness. The precision is such that even the vibrations may cause opposing needles to strike each other with resulting damage, and the requirement of fine tolerances obviously affects the manufacturing cost of the machine, which must also be rather rigid and heavy to minimize such vibrations.
In contrast, the present invention provides both a method and means for the transfer of knit loops or stitches between cylinders in double cylinder knitting machines, which method and apparatus will be inherently exempt from the problems mentioned; because common single hook needles are used within ordinary amplitudes of axial motion thereof and within ordinary limits of precision for needles, motions, and machines.